Antihunting circuit



1945; R. B. BODINE ANTIHUNTING CIRCUIT Filed March 31, 1943 l I 2 l VOLTAGE T REGULATOR ANTI- HUNT ING C/PCU/ 7' Inventor. Ralph B. Bodine,

His'Abborney.

Patented Oct. 2, 1945 I 2,386,031

UNITED STATES PATENT orrlca 2,386,031 ANTIHUNTING cmcurr Ralph B. Bodine, Schenectady, N. Y., assignor to General Electric Company, a. corporation of New York Application March 31, 1943, Serial No. 481,304 Claims. (01.171-229) This invention relates to anti-hunting cirnormal magnetic force or pull of the magnet 1 is cuits and more particularly to improvements in counterbalanced by suitable reference means, such circuits for automatic regulators. such, for example, as a spring (not shown). The

Practically all automatic regulating systems rheostatic element i and the shunt field winding tend to overshoot or hunt because of unavoidable 5 4 are connected in series with each other across time lags and inertia, either mechanical or electhe output circuit I and similarly the control eletrical or both. These efiects prevent the regument 1 and the normally fixed resistance I are lator from stopping its regulating action at the connected in series across the output circuit. exact instant when the regulated quantity is The resistance 8 has a substantially zero temretumed to normal and consequently it over- 10 perature coeilicient of resistance and it normally shoots and the regulator has to apply counterhas a resistance which is substantially higher correction. than the resistance of the winding 1 so that most In accordance with the present invention there of the circuit-voltage is consumed in the drop is provided a very simple, inexpensive and static across the resistance I and in this manner the anti-hunting circuit which is particularly winding need not be wound for high voltage and adapted for use with electrical regulators of at the Same m h Change in its resistance the direct-acting rheostatic type. Such regudue to changes in temperature will h ve ne ilators are suitable for regulating various operi le fl t n he curr nt h th i h an ating quantities associated with dynamo-electric hunting circuit I0 is connected between the Jun machines and they usually comprise a variable tion point ll ot'the' shunt field w n in 4 n resistance or rheostatic element whose resistance he h os et el me t an th i ifln I! OI is controlled by the energization of a primary the primary, control winding 1 and the r is or electroresponsive device, such, for example, as 'The anti-hunting circuit consists essentially an operating magnet. of a capacitor which is divided into two seriallyand improved anti-hunting circuit.

An. object of the invention is to provide a new onnected parts 13 and H with a resistor l5 connected in parallel circuit relation with the capac- A further object of the invention is to provide iii)! w an inexpensive and simple static-anti-hunting The series connections between the field windclrcuit for direct-acting rheostatic regulators. 8 4 n he e e 3 nd be w h P i- The invention will be better understood from cent-r01 i s l and the resistor l are companying drawing wherein there has been 51111111 circuit illustrated diagrammatically an embodiment of The operation or the circuit is as follows: Durthe invention, it will-be observed that the prining steady state conditions the energizaticn of cipal elements o1 the system are a dynamothe winding 1 will be normal and the value of electric machine I and a voltage regulator 2. the resistance 6 will be Just suiiicient to permit The machine I may, for example, be a directthe amount of current to flow through the field current shunt-connected generator having an winding 4 which is necessary to maintain conarmature 3 and a field winding 4. The armature e m; voltage on the 1 m, 5 under 18 ll-nected across an 011mm; 108d circuit conditions or speed, load and temperature which The voltage regulator comprises a rheostatic then x t. Any change in one or more or these element 6, a main or primary control element 1 r t and a normally fixed resistor 8- The primary ope a mg conditions will cause the voltage to de ment being such that an increase in energization so {hwsta'tic element is changed in the same 1 will cause a decrease in resistance or the elethereby decreasing the current in the field windment- 6'. In most regulators of this type the ing 4, and conversely a decrease in voltage on the ever, the winding fore, it is aimed in all such changes and the true spirit andscope of the invention.

circuit 5 will. cause the resistance of therheostat B to decrease.

The voltage of the junction it stays substan= tially independent of the operation of the reg latoibecause the relative resistance of the winding 1 and the resistor 8 is not varied as a result of variations in voltage of the. circuit 5. w-

4 has a relatively large inductance and therefore it resists -changes in current through it so that if the resistance oi the device 8 is decreased even slightly there will be a momentary large increase in voltage across the winding 4 because the inductance of this winding in resisting an increase in current therethrough causes it to have a momentary efiective resistance or counter-voltage which is substially equal to that of the circuit 5. Consequently, the potential of Junction it rises sub stantially above the potential or junction 62 whereby a surge of charging current flows through the anti-hunting capacitor and this surge of current will fiow'through the winding 1 in the same direction as the in current asaaosi ing capacitor, means for rheostatic element and said winding being con-' nected in series across said circuit, an anti-huntefiectively connecting .said primary control electromagnet across said control element ac which already exists therein. Consequently, en-

ergization oi the magnet l is strengthened thereby causing it to increase the rece of the rheostat 6 so as to check the action of the regulator. The strength of the anti-himting impulse flowing through the capacitor lt-ld will be proportional to the magnitude of the original change in voltage on. the circuit.

On the other hand,- circuit 5 increases above normal the action of the regulator in increasing the resistance of the rheostat 6 causes the voltage of the junction ii to fall momentarily substantially below its normal value.

around the winding 1. Itv acts to retard or re duce the rate of change oi, current in the wind- It has. been found that if the capacitor I! has Zililmicrofarads, the capacitor ll has 150 microfarads and the resistor II has ohms, the regulating system with which my invention has been tested is practicalLv dead-beat and its huntins is reduced to a minimum.- a 1 1 while there hasbeen shown described a particular embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the invention and, therethe appended claims tocover modifications as (all within as a whole has a chance tov henthe voltage of the merit across said This causes the anti-hunting current surge through the capacitor ft-M to flow to the normal current nected in' serie connected in series across winding through said capacito and means for effectively connecting'said resistor across said rheostatic element through said capacitor. I

2. In combination, a circuit whose voltage is to be maintained constant, an automatic voltage regulator comprising a rheostatic element, a primarycontrolelement'and a resistor, means incl a winding for ving'said voltage, said. rhtic element and said winding being conacross said circuit, an antihunting capacitor, a second resistorconnected in shunt circuit relation with said capacitor, means for efiectively connecting said primary smd winding through said capacitor, me for efiectively connecting the first-attic resistor across said rheostatic elementthrough said capacitor.

3, In combination, a circuit whose voltage is to be ntained constant, an automatic voltage regulator comprising a rheostatic element, a 2o I9 rat-1w 2' control client and a resistor, means inclu a winding for varying said voltage, said rheostatic element and said winding being connected in series across said circuit, an anti-hunting unit comprising a pair of serially connected capacitors and a second resistor connected in parallel with one of the capacitors, means ior eflectively connecting said primary control elewinding through 'said antihunting unit, and means for effectively connect= ing the'first-meniioned resistor across said rheostatic element through said anti-hunting unit.

4. in combination, a having a shunt field winding, a direct-acting rheostatic voltage regulator for said generator, 40 said. regulator having ,a rheostatic element connested in series with the shunt field winding of said generator, said regulator having a main control element and a normally fixed resistor connected in series across said generator, and an anti-hunting unit comprising a parallel-connected capacitor and asecond resistor connected lie-- tweenthe junction of said field winding and said rheostatic' element on the .onehand and the junction oisald control element and the firstmentioned resistor on the other hand, said connections being such that the voltage of the ea-. pacitor is equal to any difference in voltage between said shunt iield winding and said main control element.

5. In combination, a dlrect=current generator having a shunt field winding, a direct-acting rheostatic voltage regulator for said generat0r,

said regulator having a rheostaticelement connested in series with the shunt-field winding of said generator, controleleinentand a normally fixed resistor said generator, and

' an anti-hunting .nnit comprising a pair oi sewwhatlclaimasnewanddesiretosecureby Letters Patent 01 the United States '18:

1. vIncombination, a circuit whose voltage is element.

rimly-connected capacitors with a second resistor connected in parallel with one of said capacitors, said anti-huntin unit being between the Junction of said fleldwin'ding and said rheostatic element on the one hand and the junction of said control element and the firstmentioned resistor on the'other hand, said connections being such that the voltage oi! the anti-'- huntingunit islequal to any diflerence in ,voltage. between laidshunt field winding and said min: a. .sonmn direct-current generator said regulator having a main' connected j 

